lunar streamlining yields 108-mpg hwy
 

Coming back from outer space I had been contemplating Amory Lovins' 200+ mpg 'Hypercar'.
For many a moon I've tried to wrap my mind around the physics of such a car and how you could really pull it off.
So to make big mental leaps I thought I could simplify the aerodynamic part of the equation simply by eliminating it.
By inserting a 'Lunar' atmosphere into the Road-Load equation it would be quick and dirty way to look WAY forward.
Here are the assumptions ( there are always assumptions!) :
A 'typical' 1000-kg passenger car of 'typical' frontal area,and 'typical' Cd which returns 28-mpg HWY,has a Road-Load of 28-horsepower at 70-mph, constant BSFC of 0.459 pounds gasoline-per-horsepower-hour,and 'typical' all-season steel radial tires at 'typical' inflation pressures.

When the 'atmosphere' is removed,all there remains is the Rolling-Resistance and powertrain loss,which we're going to ignore.

When the aerodynamic drag is removed,the Road-Load is reduced to something on the order of 8.4-Bhp required to impel the car down the road at 70-mph.

By taking the Road-Load for one hour,at 8.4-horsepower,and 0.459 Pounds per horsepower-hour BSFC you end up with less than seven-tenths of a gallon required for the one hour of driving,or,70-miles.
This works out at 108-mpg HWY.A bit short of 200-mpg.
If you could get the BSFC of a stationary 2-stroke,compound-turbo diesel,at around 0.36-pounds/hour you still come up short.

Now if anyone has seen the Cd 0.16 "Hypercar" at Rocky Mountain Institute,Old Snowmass,Colorado,even with its light composite carbon-fiber body,200+ still seems like a 'reach.'

GM's all-composite Ultralite,at 1,400-pounds, Cd 0.19,and turbo-diesel could only manage 100-mpg,and it never went over 60-mph.

I'm a fan of RMI and I think they have done,and continue to do good work,but I have difficulty with "Hypercar's" numbers.
I realize that electrics and hybrids get 'considerations' from the EPA for CAFE purposes but 200+ mpg seems like a stretch.
I like to think that they are not,in the parlance of Louis Black,"just makin' the ---- up."

Give it a 3-main boxer, a Bugatti emblem, and a Zoltar body and IT WILL HAPPEN!!! :eek:

http://i146.photobucket.com/albums/r...er/unicorn.jpghttp://i146.photobucket.com/albums/r...cher/alice.jpg

1) Over 6+ years and close to 90K miles, my Insight has averaged 71.4 mpg, in what are not usually the best conditions for getting good fuel economy.

2) Internal combustion engines are very inefficient. Let's be generous, and say the Insight's engine averages 25% efficiency.

3) Likewise, assume an electric drive is only 75% efficient. This makes the math easy, just multiply by 3.

So with a pure electric Insight, I might expect 3 * 71.4 = 214.2 mpg equivalent.

Inadequate batteries continue to stymie straight electric cars.

The Insight's engine is an incredibly efficient one, and it mostly operates in the 30-40% efficiency range. The Insight's electric motor + inverter operates around 85% efficiency, but after losses in your charger and battery, figure maybe 75%.

100 highway mpg does not seem like a stretch to me for an ecomodded Insight driven at normal speeds. However, I've done the math on further gains, and I can confidently say no car with 20ft² of frontal area will achieve 200mpg at 55mph any time soon.

I feel you could "easily" exceed 200mpg in a streamlined feet-forwards motorcycle or trike with an Insight engine. Apparently, you can do it even with a Honda motorcycle engine: 214 mpg with DIY aerodynamic fairings on a Honda 125cc motorbike | Hypermiling, Fuel Economy, and EcoModding News - EcoModder.com

This makes the math easy, just add 25% and 75%. :p

Aerohead, is it possible that they have also reduced rolling resistance and powertrain losses?

Darn it. :mad: Here I was under the impression that we could just dream our way to 200 mpg.

75%
 

james,somewhere,in another thread we did a workup of the total energy balance of a plug-in electric car,based on coal-fired generation and found it no better,and I think,actually less than an I.C. car.
The good news,was that the electricity could be provided from renewables,however,the overall efficiency isn't any better,it's just cleaner.

Hypercar FAQ
 

I think the folks at the Rocky Mountain Institute may be a little optimistic with their modeling. But here it is straight from the Rocky Mountain Institute.

Excerpts from RMI.org - The HyperCar FAQ


Modeling by RMI suggests that full-sized Hypercar® vehicles should be able to get 90 miles per U.S. gallon of gasoline or equivalent (2.6 L/100 km) in the near term and 200 mpg (1.2 L/100 km) in the long term.


How could Hypercar® vehicles attain such dramatically improved fuel economy?
A car's fuel economy can be improved by reducing any or all of the following:
· aerodynamic drag
· rolling resistance (due mainly to tires)
· drivesystem inefficiencies (the drivesystem includes the engine and all mechanical components
connecting the engine to the wheels, such as the transmission and differential)
· energy lost during braking
· accessory loads (lights, audio system, climate control, instrumentation, etc.)
Minimizing these losses piecemeal is good, but redesigning the entire car for maximum overall
efficiency—taking an integrated, "whole-system" approach—is much better.


Ultralight Construction
... All told, it should be possible to make Hypercar®
vehicles that are 50-65 percent lighter than conventional cars of the same size.


Aerodynamics and Rolling Resistance
Today's cars are already fairly sleek, but aerodynamic drag can be further cut by 40-50 percent or more through cab-forward design, a smooth underbody, a tapered rear end, minimized body seams, and aerodynamically designed air intakes, suspension, and wheel wells.

FWIW,
Tim

R-R and powertrain
 

Patrick,I don't believe that even the low-R-R concept tires can make up the difference.
As of 1994,the Ford Motor Co. was rating a conventional powertrain at 94.4 % efficiency ( see Popular Science,Aug. 1994,pg.6 ),so it doesn't look like there's much low-hanging fruit there either.
On steel wheels ,on a railroad track you could probably pull it off.

Faq
 

Tim,thanks for the data.I found my article ( AUTOMOBILE Magazine,Nov. 1996,Pgs 48-49,by Robt. Cumberford ) and at that time, RMI was talking 380-mpg.
If they pushed the car up to speed,fired it off and engaged the power unit and drove at constant low speed with no curves,no hills,no change of velocity,no passing,etc.,they might generate some big numbers as they used to do with the Shell and Mobil Economy Runs.
For 'real world' driving,it's my opinion that they'll never get close,and it's almost a disservice to humanity to have ever broached the topic.

Of course the calculation depends on where you start measuring, but if you're just considering the in-car powertrain, then electric is far more efficient than IC, which is about the least efficient way of turning fuel into energy.

Then too, I can't help but remember all the people who've said getting 70 mpg in ordinary driving was impossible :-)

calculation
 

James,I located some brochures from Solectria I got at the Solar 500 back in the 90s.
For an 'in-car' efficiency,taking the 'best' of their products I came up with
Battery--------- 80 %
Controller------- 98 %
Motor----------- 98 %
So I agree with the 'in-car' assessment.
Looking at the 'total' energy balance,using a combined cycle coal-fired power plant for the electricity to charge the battery pack I get the following:

Power plant---------------------- 34 %----------- net 34 %
Grid------------------------------ 94 %---------- net 31.96 %
Battery Charger------------------- 90 %---------- net 28.764 %
Battery--------------------------- 80 %---------- net 23.011 %
Controller------------------------- 98 %---------- net 22.550 %
Motor----------------------------- 98 %---------- net 22.09 %

for a total net overall efficiency of 22.09 %

I ran the same genesis for a Solar Photovoltaic-powered electric car,using Space-grade Gallium Arsenide panels of 23 % conversion efficiency as the 'source' and calculated an overall energy efficiency of 17.6 %.

Reading 'The Zero Carbon Car' you're pulled into a de-fenestrated world where nothing exists beyond the electric car,and all up-stream inefficiencies are totally discounted.
The Mazda Miata glider chosen for their project while possessing only a frontal area of 17.7 sq-ft has an estimated Cd 0.45 as shown in the book.
As a gasoline car,this platform won't deliver over 42-mpg.As an EV it cannot deliver any better on an equivalent energy basis.
Southern California Edison rates EVs at 0.46 kWh/mile,not 0.25 as claimed in the book.

Phil,

There's room for debate on whether equivalent energy is a good basis for judging the merit of using electricity vs. burning gas.

There's less room for debate on what the energy equivalence conversion factor is, when the full life cycle of both energy sources are considered: around 13.4KWh/gal. From a CO2 perspective, it's 15.1 KWh/gal on US grid-average electricity.

According to Wikipedia, "The D.O.E. reports that the lumped average efficiency of electrical production and transmission in the United States, eelectricity, is 0.303 while the efficiency of refining and distributing petroleum, egasoline, is 0.830."

So remember to apply a 17% penalty to gasoline, based on the energy cost of refining and transporting it.

I've done a little math on the merit of grid-charging my 12V and traction batteries. Using US grid average power, electric comes out only slightly ahead, from a resource depletion or CO2 perspective.

But it's a complicated subject, and kilowatt-hours can not be made "equivalent" to a gallon of gas.

room
 

Robert,'complicated' puts it nicely!
Attempting to find a common denominator,moving from EV-speak to Hydrocarbon-speak has me entertaining the notion of a lobotomy.
I like your 13.4 kWh/gallon figure .I came up with 13.376 last night from a 40% maximum efficiency for IC at constant rpm and say 80% load,where the BSFC would be in the 'sweet-spot.'
I recently read William H. Kemp's 'The Zero-Carbon Car',2007.
He took a Miata and converted to BEV with a Fischer Panda marine diesel gen-set of 10 kW in the trunk.
He has 6kW of battery which is good for 12.4 miles of driving at an un-specified velocity,then the generator kicks in.
The original Miata was road-tested by CAR and DRIVER,Sept. 1989 and they recorded a road-load of 12-horsepower at 50-mph.
Kemp's Miata retains the original transmission,driveshaft and differential,and using Ford Motor Co.'s figure of 95% driveline efficiency yields 12.631 Bhp at the 'Motor.'
An 'Excellent' BSFC for a non-turbo diesel is 0.34 pound/horsepower-hour.Using the this would yield 4.2945 pounds diesel.
Dividing by 6.8306 pounds/gallon yields o.6287 gallons/50-miles,or 79.529 mpg.
I'm okay with this figure,as in 1979,Holman & Moody got 84 mpg from a Perkins turbo-diesel powered Ford Capri.
Kemp claims 234-mpg for his Zero-Carbon Car and only 12.4 miles of it's range is on battery power.
The original Miata with gasoline engine gets about 42-mpg at 50 mph according to the late Robert Carrol Parsons who owned one and endeavored to get the highest mpg from it.
I'm simply perplexed with respect to Kemp's claims.
The coup de grace is Kemp's claim that the Zero-Carbon Car was measured at 23 horsepower road load at 50 mph,whereas the original cars had only 12.
He had an overall weight penalty of 480-pounds.
I realize that the EPA has allowed automakers to use a 135-mpg value for hybrids when calculating fleet-averaged CAFE numbers,but that doesn't mean that consumers could ever hope to see numbers like this.

I don't see why this should be impossible. My Insight gets over 70, using an inherently inefficient IC engine. Replace that with a more efficient turbine or Stirling engine, make it a plug-in with the powerplant running at constant load, and you're there.

Even with its current IC engine, there are periods of cruising on the level where the lean-burn kicks in, and mpg goes well over 100. Add enough battery capacity to handle acceleration and stay in lean-burn most of the time, and you're close.

What about this, then?

http://envirofuel.files.wordpress.co...-liter-car.jpg

I think you're there
 

James,the 1st-gen Insight has 27-Bhp,yes?
At cruise speed on an open highway at 70 mph your road load should be in the neighborhood of 15.4 horsepower.( your Cd and frontal area is similar to my CRX at Chrysler Proving Grounds ).
This should have your engine operating close to it's peak BSFC,and aprox. 40 % efficiency.I doubt that your electric motor is doing the work.Let me know,I only test-drove one,never owned one.
I don't know of any company pursuing Sterling cycle or turbine anymore.Chrysler,GM,and Volvo had active turbine programs but no longer.
GM abandoned their Sterling R&D decades ago.
If you could get the engine to tolerate 1300-1500 degree F temps,you could completely lose the cooling system and have the Adiabatic Compound Turbo engine of 0.29 Lb/Hp-hr BSFC,the highest efficiency engine possible within thermodynamic boundaries.
Not even that will get you to the numbers being pushed around.
I might be missing something.Believe me,senior moments are a reality!
There are very few rocks which have not been turned over in the pursuit of higher efficiencies.
There are remarkable concept engines which were constructed with zero budget constraints however mass-production and economies of scale won't even affect raw material costs.So say the folks who follow the industry for a living.

1-liter
 

Didn't the 1st-gen 1-liter car get around 257-mpg?
Darin or someone,perhaps you,posted the road-test of this car.Everything was sacrificed for economy.Yes? And it had glacial acceleration?
I would drive it in a heartbeat,although my fellow motorists might tie me behind it and drag me to death for impeding their travel.
My mini-hypercar is kind of a 3-wheel version of this,utilizing the major portion of a motorcycle married to a roll-cage/front suspension/teardrop-taper body with some side-intrusion protection and storage compartments for daily shopping,etc..
This 1st-gen car,at Cd 0.159 is 'cleaner' than the 2nd-gen VW at Cd 0.195,but marketing folks might be scared off by the organic form and all that it implies.I don't know.
If powered for 0-to-60 mph in say 12-seconds and 80-mph cruise,she might sell to 'freaks' in Texas.The James Bede Cars remain a 'Club' car,but I've only seen two on the road since 1980.
There again,public education could turn a corner for us.You just have to decouple teacher retirement pension funds,along with municipal,county,and state government's from gas-guzzlers, the oil companies who feed the guzzle,and all the other ancillary industries and government coffers fed by fuel waste.
When ignorance is de-incentivized,we are free to educate.
P.S. we need to make the distinction between the frontal area of the 1-liter car and Jame's Insight.For a vehicle of 18.5 sq-ft frontal area to get 257-mpg does require magic.

Yes, the first VW 1L car got 283mpg (0.83L/100km), and it had a single cylinder 8.5HP diesel engine, so I'm sure it was pretty close to glacial...

Remember that the X-Prize is requiring 100mpg on an EPA Combined test -- not a ecodrive on the highway. This is a big difference. We'll see how many cars/vehicles can manage it.

The Edison2 Very Light Car is 650 pounds -- a little *less* than the VW 1L car, and it has a ~40HP turbocharged 250cc engine running E85 and they have devised a special throttleless intake/exhaust recirculation system that makes it as efficient as possible. And they got 83.3mpg.

We have no "official" results from anybody else.

Arvw
 

Neil.do you remember the Volkswagen ARVW from the late 1970s?
I don't have my materials with me,but it seems like that 'car' was getting 70+ mpg at 90-mph,and still around high 17s at over 200 mph.
That was at Cd 0.15.
My gut tells me that if 'adequately-powered' the 1-liter would still be a 'rock-star' of mpg for a commuter vehicle.
My CRX has only 60-Bhp but I can get up to freeway speed on any on-ramp,no problemo.
I haven't seen the Edison car,I'll have to check that out.Thanks!
P.S. these cars could run two-abreast in an H.O.V.Lane.